Potassium carbonate is mainly prepared by ion exchange and electrolysis methods

Potassium carbonate, as an important inorganic chemical raw material, has significant technical and economic value in both its preparation process and application fields. The following is a systematic explanation from two dimensions: preparation process and application field:

1、 Preparation process

Ion exchange method

This method uses potassium chloride and ammonium bicarbonate as raw materials, and achieves ion displacement through ion exchange resin. The specific process includes:

Resin transformation: Potassium chloride solution is passed through a strong acidic cation exchange resin (such as 001 × 7 type) to adsorb potassium ions (K ⁺) and convert them into potassium type resin (R-K).

Ammonium type conversion: Treat potassium type resin with ammonium bicarbonate (NH ₄ HCO ∝) solution, replace potassium bicarbonate (KHCO ∝) solution, and convert the resin to ammonium type (R-NH ₄ ⁺).

Crystallization and calcination: Evaporate and concentrate potassium bicarbonate solution to 40 ° Be ', cool and crystallize to separate potassium bicarbonate crystals, and then calcine at 500 ° C to decompose into potassium carbonate (K ₂ CO3).

Technical features: This method can achieve a product purity of over 99%, but there are problems such as high energy consumption for resin regeneration and ammonia nitrogen content in wastewater, which require supporting ammonia recovery equipment.

Electrolytic method

This method prepares potassium hydroxide by electrolyzing potassium chloride solution, and then reacts with carbon dioxide to generate potassium bicarbonate. The specific steps include:

Electrolytic alkali production: Electrolytic potassium chloride aqueous solution generates potassium hydroxide (KOH) and chlorine gas (Cl ₂), which can be further used to produce hydrochloric acid or sodium hypochlorite.

Carbonization reaction: Potassium hydroxide solution is introduced into carbon dioxide (CO ₂) for carbonization reaction, generating potassium bicarbonate (KHCO ∝) solution.

Calcination and purification: After evaporating and concentrating potassium bicarbonate solution, it is calcined and decomposed into potassium carbonate.

Technical advantages: This method can co produce by-products such as chlorine gas and hydrochloric acid, with significant comprehensive economic benefits, but requires control of carbonization reaction conditions to avoid the generation of by-products.

Other methods

Plant ash extraction method: The traditional method involves burning plant straw to obtain potassium ash, which is then soaked, filtered, and evaporated to produce potassium carbonate. However, the purity of the product is low (about 80%) and is only suitable for agricultural use.

L ü bulan method: using potassium sulfate as raw material, mixing and calcining with coal powder and limestone to produce black ash, which is then extracted, filtered, and evaporated. However, the process is complex and energy consuming, and has been gradually phased out.

2、 Application Fields

Industrial sector

Glass manufacturing: As a flux to reduce the melting temperature of glass, improve the transmittance and chemical stability of optical glass, it is widely used in fields such as optical instruments and flat glass.

Welding rod production: As a slag forming agent in the electrode coating, it improves the welding process performance and enhances the quality of the weld seam.

Dye industry: used in the production of vat dyes, as auxiliary agents for printing, dyeing, and ice dyeing processes, to enhance the color brightness and wash resistance of dyes.

Dry powder fire extinguishing agent: mixed with soda ash (Na ₂ CO ∝) to make dry powder fire extinguishing agent, which extinguishes fires through chemical inhibition, suitable for electrical and oil fires.

Other industrial applications include ink production (pH adjustment), photographic drugs (developer), polyester synthesis (catalyst), explosive production (oxidant), electroplating (buffer), leather making (degreasing agent), ceramics (glaze flux), building materials (cement additive), etc.

In the field of agriculture

Fertilizer: As a potassium fertilizer, it supplements soil potassium elements, promotes crop root development and fruit enlargement, and improves yield and quality.

Soil improvement: Adjust soil pH value, improve acidic soil structure, and enhance soil water and fertilizer retention capacity.

Other fields

Water treatment: used for boiling cotton cloth and defatting wool, removing impurities by adjusting pH value, and improving textile quality.

Medicine and daily chemical products: used for the production of potassium soap (such as shampoo, shower gel), pharmaceutical intermediates (such as antibiotics, vitamins), etc.

Food industry: As a food additive (E501), it is used to adjust pH value and improve taste, but the dosage needs to be strictly controlled to avoid excessive sodium intake.

3、 Market Status and Development Trends

Market situation

The global production capacity of potassium carbonate is about 1.1 million tons per year, with China accounting for about 40%. The main production enterprises include Salt Lake Group, Zangge Holdings, and Migao Group.

The global market size is expected to reach approximately $1.5 billion in 2023, and is projected to increase to $2 billion by 2028, with a compound annual growth rate (CAGR) of approximately 5.8%.

China's production in 2023 is about 442000 tons, with a demand of about 446000 tons. The supply and demand are basically balanced, but high-end products such as electronic grade potassium carbonate still need to be imported.

Development Trends

Technological upgrade: The ion exchange method is developing towards continuity and automation, while the electrolysis method is optimizing towards energy conservation, consumption reduction, and comprehensive utilization of by-products.

Application expansion: The application in the fields of new energy (such as electrolyte additives for lithium-ion batteries) and environmental protection (such as flue gas desulfurization) is gradually expanding.

Policy support: China's "dual carbon" goals promote the research and development of green production processes, such as using salt lake brine to directly prepare potassium carbonate, reducing energy consumption and carbon emissions.